Radio signaling system



Nov. 11, 1930. A. BAILEY Er AL 1,730,952

I RADIO SIGNALING SYSTEM File ad April 15,1927

Lg 110 R0 flesz'rvd' 'ynat J INVENTORS Jamm 5. WM

ATTORNEY Patented Nov. 11, 1930 UNITED STATES AUSTIN BAILEY, OF FREEHOLD, NEW JERSEY.

AN.D SAMUEL WINTHROP' DEAN, OF

HOULTON, MAINE, ASSIGNORS T0 AMERICAN TELEPHONE AND T'ELEGRAPH' COM-- PANY, A CORPORATION OF NEW YORK RADIO SIGNALING SYSTEM Application filed April 13,

This invention relates to radio transmission systems, and particularly to arrangements in such systems for combining the outputs of two or more circuits.

In radio receiving systems in which it is necessary to maintain a high degree of selectivity in reception, highly directive antenna systems are particularly desirable. Directive antenna systems are usually obtained by combining the outputs of several antennae, which may or may not be themselves directive. Such systems of antennae are known in the art'as antenna arrays. This invention particularly relates to a means for combining the outputsof several antennae constituting the component parts of such an array, and equally well for combining two or more output circuits derived from a single antenna.

One form of antenna which has been found to be highly successful in-practice is known in'the art as the wave antenna. While this invention will be disclosed with particular reference to its use in connection with a wave antenna or an array of wave antennae, it will be apparent that it is applicable to any antenna array.

In the ordinary use of Wave antennae, as is well known in the art, a small fraction of the interference or noise voltages developed in the surge resistance of a wave antenna is used to balance out undesired interference and noise received by the antenna from a directiondiiferent from that of the desired signal. This process of neutralization is termed compensation and serves in effect to produce zero or negligible reception at any desired angle, that is, at any angle different from the angle of the desired signal.

The directivity of a receiving system will be increased by the use of parallel wave antennae spaced aparta certain fraction of a wave length in a direction atright angles to that of the desired signal, each wave antenna, however, being substantially parallel to the line of travel of the, desired signal. Such an arrangement is often referred to as a broadside wave antenna system, and its effect in general is to increase the directivity or rather the discrimination against signals or noise'coming from other than the desired 1927. Serial no. 183,532.

direction In such a system, compensation may also be employed to reduce the re'cep tion' of interference or noise'to a considerable extent.

In accordance with the present invention, it is proposed to bring to a common point not only the desired'signal's impressed upon two or more Wave antennae, butalso voltages representing undesired signals or interferences which are set up in the antennae by Waves or disturbances in space. The signals which are brought to the common point from the Wave antennae will be combined under suitable conditionsof-phase and amplitude, and similarly, the voltages representing undesired signals or interference will be also combined under similarfconditions of phase and amplitude. The latter voltages will then be utilized to balance out noise and interference coexistent with the desired signals in the terminal circuit of the said Wave antennae.

In order to accomplish the object of this invention, means will be provided for combining the outputs of the Wave antennae so that there will be an additive effect for the desired signals in the output of the combining means, though there will be zero or negligible interaction between the input circuits of the'combining means. In other words, the currents flowing in the input circuits will be mutually independent and non-reactive, and still these currents will be combined additively bythe combining means. One form of combining means, which will be described hereinafter, comprises a hybrid coil having a plurality of windings, one of which is utilized to receive desired signals impressed upon one wave antenna, another of which is utilized to receive desired signals impressed upon another wave antenna, one or more of which are connected to a balancing network of a well-known type and another one or more of which are connected to an output circuit which may lead to a radio receiver. In the particular form of hybrid coil to be described hereinafter, the balancing network has an impedance which substantially equals the impedance looking into the output or receiving circuit. Moreover, desired -signals' ray;

impressed upon one of the windings by one of the wave antennae cannot be transferred to another of thewindings upon which are impressed similar desired signals by another of the. wave antenna, and vice versa. Also,

if the desired signals impressed upon the respectivewindings of the hybrid coilare equal inam v litude and in phase, the output or re- L I .ceiv ngc rcuit ofj-the hybrid coil wil receive theentire energy of the desired signals.

While this invention will be pointed out with particularity in the appended'claims, the

:invention'will nevertheless be better understood from the detailed description herein-' after following when read in connection withthe accompanying drawing in which Figure 1 showsone form of receiving system to which ng oneelement ofa combining circuit.

, received;

this invention has been applied,the system comprising wave antennae connected in broadside, and Fig. 2 represents a hybrid coil form- Referring to'F-ig. l of the drawing, two

. wave antennae A and B are shown, each con sisting of two or more parallel wires extend- I ing 7 across the country substantially parallel to the direction of travel of the signals to be It is to .be definitely. understood,

7 ahoweve'r, that the principles ofthis invenually grow in'aii plitude as sired to receive the signaling wave which 1 "use may be applied to any number of wave antennae orrother antennae constituting an ar- Assuming that each antenna extends,

forezi-zample, from east to west, then a signal which, Comes from the east gradually builds up. by increments, reachingits'inaximum value at the west end of the antenna. In other words,-the" current in the antenna willgradtravels along itssurface- Yet, if it is deapproaches the antenna fromthe eastern direction, the amplitude of the current set up by the signaling wave at the eastern terminal of the antenna will be extremely small, if not ne li ible while at the western terminal the amplitude of the current will be considerablylarger and a maximum; I It is some times necessary to'locate the receiving apparatu's, near the eastern terminal of the antenna. .In order topermitsuch a location,the

' nal-in a reflection transformen such asltT so that the antenna conductors serve not only antennais terminatedfat the ,western termito pick up the wavesin spacebi'it also maybe employed as a transmission line-for transmite ting from the western terminal to the eastern terminal thecurrents resulting frointhe voltage built'up' in the antennae Themidpoiiit of the secondary windingfof the-reflection transformerBT, isiconnected through the primary winding of that transformerjto ground. By means ofthese connections,.the

' the, priniaryrwindingi of-the reflection trans-T fornierRT -and the voltage created thereby antenna currentflows to ground through across the winding bridged, acro'ssthe conducthe signaling wavetors of the antenna A'causes a flow of current over the conductors as a metallic c1rcu1t. At

the eastern terminal of the antenna, such as A, another transformer ST is located, the

midpoint of the'pi-imary winding of which is connected to ground through the primary winding of anothertransformer GT which is so constructed thatwith its attached circuits easterniterminal of the antenna Aland ground is often spoken of as thesurge resistance; The transformer ST associates the metallic it servesto x01561 15? fet d Edam 2115812128 The resistance thus; interposed between the circuit of the antenna A with a transmission line A this line leading to the receiver by way. of apparatus tov be subsequently de? 1 scribed. The voltage resulting from an unde- 1 sired signal builds up in each conductor of antenna A in the opposite direction, 1. e., from west to east, along the antenna, and substan-: tially equal current resulting therefroniwill I flow'throughthehalves of the primary wind ing of the transformerST oppositely to a ground (by virtue of the connection to ground of the midpoint of the primary winding of the transformer S1 ,thence throughthepri marywinding ofthe transformer GT No effects will; be produced .in t-he'secondary it winding of the transformer ST andaccor dingly, the local line Aiwill befsubstantially vunaffectedby such currents.

A wave antenna of thetype described 'eX- hibits considerabledirectional selectivity,-re-v to introduce noise and interference into the 1 receiving circuits.- The amount ofv noise or interference introduced bysignals different from the'desired signals willqdepend upon the direction from whicl they are coming. Signals coming, for example, from the north and the south, i. e., perpendicularito thean-- tennae, will hardly be received,-i' f at all; Yet,

it is important to compensate or balance out the noise or interference derived from signals coming from still other directions. Y So far, the apparatus has been described with respect to asingle wave antenna. When a plurality-ofantennae are employedionly.

twoof which are shown herein'forillustrative purposesyeach will bevprovided with equipment similar to that described in con nectionwith antenna--A. Asignal moving in the" direction from east. towst impressed upon the, antenna B .will be transmitted to the reflection, transformer RT and backgover the conductors ofthe antenna to a local cirfcuitB The current of undesired signals picked up antenna Bwill be substantially m ee a non-effective in the localcircuit B connected to the secondary winding of the transformer ST only a small fraction of the said undesired signals will be superposed upon the desired signals in the circuit B The desired signal components from the antennae A and B, flowing in the local .circuits A and B may be combined in a common circuit C by means of a hybrid coil HQ, the details of one form of which are shown in Fig. 2 of the drawing, It is, of course, necessary for a proper combination .of these signal components that they be impressed upon'the hybrid coil HG in phase with each other. It isalso necessary in prac tice that the signal components from the antennee A and B be impressed upon the hybrid coil HG at substantially the same amplitude. These results may ordinarily be obtained by making the circuits A and B of substantially equal length. Yet, if the geographical situation is such that these lines may not normally be of substantially equal length, they may be made of the same length by providing indirect routes between the hybrid coil H0 and the eastern terminals of the antennae. As an alternative, the shorter line may be made electrically of the same length as the longer line by interposing in the shorter line an artificial line section which may consist of a phase shifter P and an attenuator L introducing phase shift and loss equivalent to the difference in length between these lines. I

In a similar manner, the noise or interference currents flowing through the primary windings of the transformers GT and GT of the antennae A and B, respectively, may be transmitted to a h brid coil HO over lines A and B respectively, and combined in a circuit C by means of a similar hybrid coil HC Here again, the components taken from the respective antennae must be impressed upon the hybrid coil HC inthe same phase and equal amplitude with each other. Moreover, the lines A and B should be of substantially equal length or should be made electrically of substantially equal length, as described hereinabove. A phase adjuster P and an attenuator L both of which are well known in the art, may be included in one of the lines, such as B Obviously, the phase adjuster P serves the purpose of adjusting the phase of the compen- .sating current coming through the transformer CT to equal the phase of the compensating current coming through the transformer GT phase equality being necessary to a suitable additive combination of the respective currents. Similarly, the attenuation adjuster or attenuator L may, if desired, be varied so that the current flowing in the local circuit B is substantially equal in magnitude to the current flowing in the local circuit A a Thehybrid coils H0 and H0 are connected to balancing networks N and N respectively, these balancing networks comprising preferably series and shunt resistive and reactive elements, as is well'known in As described hereinbefore, the signal currents are combined in the common circuit C together with noise and interference currents resulting from undesired signals or disturbances picked up by the wave antennae A and B. The compensating noise and interference currents brought together by circuits A and B are combined in a common circuit C In order to free'the signal currents from the noise and interference currents superimposed thereon, the compensating noise currents from the circuit C are impressed on the circuit R0 together with all currents from the circuit C through the medium of the hybrid coil no which is preferably of the same general type as hybrid coils HC and It is, of course, necessary that the compensating current and noise or interference current to be compensated shall be of substantially equal amplitude and 180 out of phase. Accordingly, a phase shifter P and an attenuation adjuster L are interposed between the hybrid coil HC and the hybrid coils PIC and H0 respectively. he phase adjuster is manipulated to bring about the required 180 phase variation necessary to properly combine the current in the circuit C to be compensated with thecompensat-ing current in the circuit 0 for effective neutralization. The attenuation adjuster L serves to render the magnitude of the compensating current in the circuit C the same as that of the current to be compensated in the circuit C this being a condition which must also be fulfilled for effecting neutralization of these combining currents. A balancing network N similar in character to balancing networks N and N is connected to the hybrid coil HC this'balancing network having an impedance substantially equal to the impedance of the circuit RC connected to the hybrid coil. After the adjustments above mentioned have been made for the phase and magnitude, ofthe compensating currents as well as'for the currents to be compensated, the receiving circuit RC will receive the desired signals substantially free from the effects of the noise or interfering currents.

In using the system of this invention,-the adjustments required for combinationof currents flowing to circuits may be made with a minimum of effort. The adjustmentsnecessary for the proper combination of the signal currents derived from the various antennae, as well as the adjustments necessary for the proper combination of the compensating currents of these antennae, are relatively stable and fixed 1n their nature, requirin g only slight changes with time. Due to the varied conditions'br'ought" about by the impressionof signals from various angles upon the wave antennae, it is'necessary at intervals to 're adjust the phase shiftersv and attenuators representing'thecompensating apparatus in order to preserve the required degree, of balance againstthese waves. 7 In Fig. 2 of the drawing thereis shown a, hybridicoilarrangement for combining the currents flowing in two separate circuits. The form of arrangement represented in the figure comprises two transformers, each of which has, upon its core,-three windings each wound 111 a definite direct-ion. The w ndlng 1N of itransformer T is connected to the input circuitiC and the windingWg of'transformeriT to an input circuit C The windings 'W and VV of transformersT and T respectively, are connectedto the output or receiving circuit RC, while Windings'W and WV 'of 'the respective transformers are in "SBIlGS wlth a balancing network N.

.The windings of the transformersT and Tgare symmetrical, the corresponding w1ndngsof' these transformers havingthe same values. Moreover, a balanced condition exists between the balancing network N and the 'recelvmg circuit RC; The transformer arrangement shown herein constitutes in effectacombinin'g circuit whichis adapted to a combine currents 'fiowing in circuits C and C for transmission to the circuit Having in mind theforegoing description f the transformerarrangement, the manner stood from the following description.

in-which it functions to combine the currents of two separate circuits will be better underit'be assumed thatenergy is to be transmitted over the circuits O and C to the output or receiving circuitRQ Accordingly, the flow of currents in the windings W and of transformers T .and T may be assumed to be inthe directions indicated by the arrows adjacent'thereto. These currents in windings I W and W will induce potentials upon windings: l/V and W and W and W.;, respectively, ,which will tend to cause the flow of currents therethroughl The 'windings W and 'Wgare so arranged that the flowof currents therethroughdue to the normal flow of currents in c'ircuitsC and C as indicated,

will'aid each other, whereas windings 'W and W are differentlyarran'ged so that the flow of currents therethro'ugh will normally oppose each other under the same circumstances. 'The arrows adjacent to these windings represent the polarity of the potentials normally impressed acrossthese windings.

' If the currents flowing'in circuits G and C are of equal amplitudes and of the' same phase, equalvoltages will'be induced in Let.

windings and W5 which" are oppositely directed sothat there "is no :resultant effect.

in the circuit of the network N. Under the cuit RC will receive all the energy from the beunequal, and current will flow through the balancing network N. ofana'mount propor-I ftional to the difference between the poten-e tials impressed across these windings. Fur- 'thermore,"if the currents flowing in circuits:

same conditions, the output or receiving cir- 6 C and G iwere'of equal amplitudes; and of opposite phases, the potentials set up, across;

the terminals of windings W and-W will stillbe ofequal magnitudes, and yet these currents would become substantially neutralized by virtue of their'presence in the output or receiving circuit BC in phaseopposition.

Inthi's case the'entire energy; from circuits C and C will be dissipated in the network- N. This propertyof the hybrid coil isjmade use of when undesired signal'or interference currents are combinedin phase opposition, as in the compensating circuit described'hereinabove. ,fFurther'mo're, if the impedance of the network N is substantially'equal to that a presented by the receiving circuit RC,-curmitted to circuit C and vice versa; There fore there is no interaction betweencircuits '100 G and C rents flowing in circuit C will not betran's- The symmetrical transformers T and T g each containing three windings, constitute the means for combining the energy present in two separate circuits. The invention is not, however, limited to the particular ar rangement shown, since'it'will be apparent to those skilled in the art that a different rearrangement of thejelements shown, or of equivalent elements, might be employed to produce a s1m1lar comblning circuit. a

"While the invention has been disclosed in connection with two wave antennae,'.it will be apparent that it is applicable to any'number of antennae. Thus, for example,if a

broadside antenna systeme'empl'oying three combining of their signal currents "in the manner shown in Figfl. Such combined currents could then be applied to another hybrid coil, together with the signal current '115' antennae were used, the outermost antennae I could. be connectedwith a hybrid coil for the from' themiddle antenna to produce are sultant representing the combination of all of the said currents. In like manner the com- 'pensating' currents from the three antennae could be combined by bringing together the interference from the outer antennae and'combining the resultant with interference f'rom theinner antennae. These compensating cur rents could then be combined with the re sultant signal current (upon which noise or interference is superimposed) by a coil such as HQ, so as to effectively neutralize such noise or interference.

It is desirable to point out that the transpositions in the transmission lines A and A connected with the antenna A are for the purpose of preventing cross-talk or other interference between the currents flowing over these lines.

IVhile this invention has been shown and described in a certain particular embodiment, it will be clearly understood that the general principles of this invention may be applied to other and widely varied organizations, without departing from the spirit of the invention or the scope of the appended claims.

1 W hat is claimed is:

1. In a signaling system, the combination with a plurality of antennae, constituting an array, of a common receiving circuit, a transformer arrangement comprising a plurality of windings, a plurality of transmission paths, one transmission path extending from each antenna to a corresponding winding of the transformer arrangement, and a balancing net work connected to certain of the windings of the transformer arrangement, said balancing network exhibiting an impedance substantially equal to the impedance of the common receiving circuit, said common receiving circuit being also connected to certain of the windings of the transformer arrangement.

2. In a signaling system, the combination with a plurality of substantially parallel wave antenna, separated a predetermined distance and constituting an array, the longitudinal axis of which may or may not be substantially parallel to the line of travel of desired signals, of a common receiving circuit, a transformer arrangement comprising a plurality of windings, a plurality of transmission paths, one or more transmission paths extending from each wave antenna to corresponding windings of the transformer arrangement, and a balancing network connected to certain of the'windings of the transformer arrangement, said balancing network exhibiting an impedance substantially equal to the impedance of the common receiving circuit, said common receiving circuit being also connected to certain of the windings of the transformer arrangement.

3. In a signaling system, the combination of a pair of wave antennae placed side by side a predetermined distance apart, each being substantially parallelto the line of travel of desired signals, a transformer arrangement comprising a plurality of windings, a pair of transmission paths, one extending from each wave antenna to a corresponding winding of the transformer arrangement, a common receiving circuit connected to other 4. In a signalinglsystem, the combination of a pair of input circuits, an output circuit, a balancing network, and a transformer ar-, rangement to which said input circuits are symmetrically connected, said transformer arrangement being also connected to said output circuit and being adapted to permit the free transmission of signals from said input circuits to said output circuit without interference of interaction between said input circuits.

5. A system for combining the currents flowing in a pair of circuits so that the currents in either of the circuits will not be impressed upon the other circuit, comprising a transformer arrangement having a plurality of windings, one of which is connected to each of said circuits, said circuits being con-v nected symmetrically with respect to the corresnonding windings of the transformer arrange1nent, a receiving circuit connected to certain of the windings of said transformer arrangement, and a balancing network connected to the rest of the windings of said transformer arrangement.

6. The combination of a pair of transformers, each including three windings, two input circuits each connected to a corresponding winding of one, of the transformers, a receiving circuit connected serially with respect to a pair of said windings, one corresponding to each transformer, and a balancing network connected serially between the remaining two windings, one also corre sponding to each transformer. i

7. The combination of two transformers, each transformer including three windings arranged on a common core, each winding in one transformer being similar in all respects to a corresponding winding in the other transformer, an output circuit connected serially between a pair of similar windings of said transformers, a balancing network also connected serially between another pair of similar windings of said transformers, and two input circuits, each connected serially to the remaining winding of each transformer.

8. The combination of two transformers each havingone'. primary winding andtwo balancing network simulating the impedance v of said output circuitconnected in series with theot-her secondary winding of each trans former.

Ingtestimol ly Wheredfl hairef signed my name-'to' this specification this 3 1st'day of fMa-rch 1927. V

SAMUEL' INTHROP DEAN'.-- 'In testimony whereof 'I have signedmy naineto this specificationthis 31st day of ,March,'1927. 1 r

I AUSTIN BAILEY; 

